CPP32 APOPAIN IS A KEY INTERLEUKIN-1-BETA CONVERTING ENZYME-LIKE PROTEASE INVOLVED IN FAS-MEDIATED APOPTOSIS

Cysteine proteases of the interleukin 1 beta Converting Enzyme (ICE)/C ED-3 family have been implicated in the effector process of apoptosis in several systems, including Fas-mediated apoptosis. We have recently isolated and partially characterized a protease present in extracts f rom anti-Fas antibody treated Jurkat T cells that promotes apoptotic c hanges in isolated nuclei (Schlegel, J., Peters, I., and Orrenius, S. (1995) FEES Lett, 364, 139-142), We now show that this protease cleave s poly(ADP-ribose) polymerase (PARP) with high efficiency and specific ity. Both PARP proteolysis and the proapoptotic effects of the proteas e are inhibited by nanomolar concentrations of a selective inhibitor o f apopain (CPP32), while an inhibitor of IL-1 beta converting enzyme i s much less effective, requiring micromolar concentrations for the inh ibition of the isolated protease. Kinetic analysis of the isolated pro tease reveals kinetic constants similar to those reported for apopain, The isolated protease is recognized by antibodies specific for CPP32/ apopain but not by an anti-ICE antibody. Furthermore, a selective inhi bitor of apopain prevents Fas-induced apoptosis in intact Jurkat T cel ls, We therefore conclude that CPP32/apopain is activated in Fas-induc ed apoptosis.